Heavy duty vacuum cleaner

ABSTRACT

A first frame is supported by wheels and a second frame is pivotally connected at one of its ends to the first frame on the axis of rotation of those wheels. Also secured to the first frame are a rotating horizontal-axis brush and other conventional features of a sweeper with vacuum. The free end of the second frame is supported by casters. Wedges are mounted at either side and on the top of the free end of the second frame. A threaded shaft is mounted on the first frame such that it passes over those wedges and carries blocks which engage the inclined surface of the wedges. The blocks travel across these inclined surfaces when the shaft is rotated, since they are restrained by channels from rotation with the shaft. The travel of the blocks adjusts the spacing between the first and second frames to raise and lower the first frame and its equipment with respect to the surface being treated while the angular relationship between the second frame and the floor remains substantially unchanged.

United States Patent Nise et al.

11 1 3,678,524 1451 July 25,1972

[54] HEAVY DUTY VACUUM CLEANER [72] Inventors: Wilfred C. Nise, SpringLake; Dale E.

Lowder, Muskegon, both of Mich.

Clark Floor Machine Company Division of Studebaker Corporation,Muskegon, Mich.

[22] Filed: March 19, 1970 [21] App]. No.: 20,909

[73] Assignee:

[52] U.S.Cl ..15/49, 15/351, 15/354 [51] Int. Cl ..A47l 11/00, A471 5/34[58] Field of Search ..15/49-52, 98, 99,

2,691,791 10/1954 Humphrey ..15/354 UX Primary Examiner-Leon G. MachllinAttorney-Price, Heneveld, Huizenga & Cooper [57] ABSTRACT A first frameis supported by wheels and a second frame is pivotally connected at oneof its ends to the first frame on the axis of rotation of those wheels.Also secured to the first frame are a rotating horizontal-axis brush andother conventional features of a sweeper with vacuum. The free end ofthe second frame is supported by casters. Wedges are mounted at eitherside and on the top of the free end of the second frame. A threadedshaft is mounted on the first frame such that it passes over thosewedges and carries blocks which engage the inclined surface of thewedges. The blocks travel across these inclined surfaces when the shaftis rotated, since they are restrained by channels from rotation with theshaft. The travel of the blocks adjusts the spacing between the firstand second frames to raise and lower the first frame and its equipmentwith respect to the surface being treated while the angular relationshipbetween the second frame and the floor remains substantially unchanged.

17 Claims, 6 Drawing Figures HEAVY DUTY VACUUM CLEANER BACKGROUND Thisinvention relates to an improvement in means for controlling the spacingbetween a floor treating element and the floor.

Almost any type of cleaning machine utilizes a floor treating elementsuch as a brush or its equivalent in performing its function. Examplesinclude floor scrubbers, polishers,

types of machines.

In controlling the relative elevation of the brush means, it is alwaysdesirable that the degree of contact between the brush means and thesurface being cleaned remain constant throughout the length of the brushmeans. Most elevation control mechanisms require the use of frames whichare very sturdy from side to side in order to achieve this uniformcontact. This is because the control is located on one side of themachine and its action must be transmitted to the other side by thesturdy frame. If the frames are structurally inadequate, the degree ofcontact will be irregular and may even vary during operation if thestructure of the frame permits it to warp or to rock on the controlmechanism.

Many elevation control mechanisms are not suitable for use on machineswhere it is desireable to use casters as an integral part of the controlmechanism. Such mechanisms do not allow the caster pintles to remainperpendicular to the surface being cleaned. The result is that thedegree of contact between the brush and the surface being cleanedvaries, depending on whether the machine is being moved forwardly orrearwardly.

Other mechanisms are designed with the control activation element, suchas a knob or lever, located at the rear of the machine. These mechanismsare unacceptable for use in a variety of machines such as those havinglarge bulky bags or handles. Furthermore, rear activated controlmechanisms frequently necessitate the use of very sturdy and heavycontrol frames.

' SUMMARY OF THE INVENTION This invention comprises generally a firstframe means and a second frame means pivotally connected to it. A brushmeans is mounted on the first frame means at some distance from thepivot axis between the two frame means. A support means is mounted onthe second frame means, also at some distance from the aforementionedpivot axis. There is a cam means between said first and second framemeans located at a distance from the aforementioned pivot axis. Anactivating means is provided for activating said cam means whereby avariation can be achieved in the angular relationship between the firstand second frame means.

Thus, one object of this invention is to provide an elevation controlmechanism which is simple, effective and economical in construction.

Another object is to provide a mechanism which effectuates a uniformdegree of contact between the brush means and the surface being cleaned,without the necessity of using a very heavy-duty frame.

This invention also allows one to use casters to support the secondframe means since it keeps the caster pintles generally perpendicular tothe surface being cleaned.

This invention further provides a mechanism which is adaptable for usewith a side-mounted activating means, such as a knob mounted on the sideof the machine rather than on its rear. Further,the cam and wedge systemis utilized with a minimum of force applied to the actuation knob orhandle.

Finally, the use of elaborate lever mechanisms and the like areeliminated.

BRIEF DESCRIPTION OF THE DRAWINGS These andother objects and advantagesof the invention can be visualized by reference to the appended drawingswherein:

FIG. I shows a bottom perspective view of a heavy-duty sweeper;

FIG. 2 shows aside view of a heavy-duty sweeper with a portion beingbroken away;

FIG. 3 shows a perspective of the machine with the front being brokenaway along Ill-Ill of FIG. 2,- and with the vacuum hose and impellerhousing not shown;

FIG. 4 shows a fragmentary elevation taken along Ill-Ill of FIG. 2;

" FIG. 5 shows an elevation of an arm end and wedge taken on line V--Vof FIG. 4; and

FIG. 6 shows an elevation of an arm end, wedgeand cam taken on lineVI-VI of FIG. 4.

PREFERRED EMBODIMENTS The invention is here embodied in a heavy-dutysweeper with vacuum pick-up. Besides the conventional elements found insuch an apparatus, it includes a first frame 10, (FIG. 1) a second frame20 pivotally secured thereon, a pair of wedges 30 on the free end ofsecond frame 20, threaded shaft 40 onfirst frame 10, a pair of blocks orcams 50 (FIG. 2) on threaded shaft 40 and a pair of channel members 60on first frame 10.

First frame 10 includes a platform 11, having sides l2-and back 13 bothdepending downwardly therefrom (FIGS. 1, 2 and 3). The bottom edges ofsides 12 slope upwardly from front to back. Extending across the frontof frame 10 is a housing 14 in which a brush 2 is mounted]. Frame 10 canreadily be fabricated in any suitable manner such as being a casting orformed from sheet material.

Rotatably attached to each side 12 of frame 10, near the rear thereof,is a large wheel 3 (FIGS. 1 and 3). Each axle 3a of each of said wheels3 is secured to a side 12 and extends inwardly therefrom. It issufficiently long that it extends through the hub of wheel 3and providesa stub shaft upon which second frame 20 is rotatably mounted.

Mounted on platform 11 are other conventional elements such as a motor4, an impeller housing 5 and a vacuum hose 6 (FIGS. 1 and 2). Theseelements are enclosed by a cover 7. A handle 8 is secured to the rear offrame 10 and extends upwardly therefrom. .Mounted on handle 8 is a bag 9which receives litter from impeller in housing 5. All of these elements(except the mounting of the second frame) cooperate in a conventionalfashion and do not of themselves form of this invention.

Second frame 20 (FIGS. 1 and 2) comprises a U-shaped member including apair of arms 21 and a cross piece 22. Each arm 21 is U-shaped in crosssection. The ends of the arms 21 are joined through cross piece 22 whichis rigidly secured to both arms as by bolting or welding. A caster 23 isconnected to each arm 21 adjacent the cross piece 22. The non-joinedends of arms 21 are each pivotally mounted on the inwardly extendingstub shaft of axle 3a.

Wedge members 30 can best be seen in FIGS. 3, 4 and 5. Each includes anattachment flange 31 (FIG. 5) whereby it is rigidly secured to the endof an arm. 21 adjacent cross piece 22. A wall 32 extends upwardlyfromattachment flange 31 at right angles thereto and is triangularinconfiguration (FIGS. 3 and 4). Then a flange or ramp 33,. comprisingan inclined plane extends outwardly from wall 32 at right anglesthereto. Ramp 33 has an open ended slot 34 in its uppermost end toprovide clearance for the hereinafter described shaft 40.

The threaded shaft 40, shown best in FIGS. 1, 3 and 4 passes through theleft wall 12 of frame 10,. as viewed in FIGS. 1, 2 and 3. Shaft 40passes over the wedges 30 mounted on the a part ends of arms 21. Knob 42is fastened on that end of shaft 40 which is outside wall 12 and awasher is fixed to shaft 40 just inside of wall 12. In this fashion,shaft 40 is fixed against axial movement. The opposite end of shaft 40is rotatably mounted in bracket 41 which is integrally secured to theunderside of platform 11, near the right wall 12 of frame 10.

Each of the two blocks 50 includes two flat sides 53, two ends 54, agenerally flat top 55 and a rounded nose portion 52 (FIGS. 3, 4 and 6).A threaded opening 51 passes through block 50 between ends 54, wherebytwo such blocks 50 are threaded onto shaft 40. The blocks 50 are free totravel over the surface of ramp 33. The travel of right block 50 islimited by bracket 41 on one side and by a cotter key 43 or equivalentstop on the other side. The travel of left block 50 is limited by cotterkeys 43 or equivalent stops located on either side thereof on shaft 40.

Each of the two channels 60 includes a top 61 and side walls 62 (FIG.6). Each channel 60 is approximately equal in length to the distancewhich a block 50 is free to travel. Each channel 60 is integrallymounted to the underside of platform 11 of frame as by welding top 61thereto. Each channel 60 is located such that its side walls 62 embracea block 50. Thus, each side wall 62 is located closely adjacent a side53 of each block 50, such that each block 50 is restricted againstrotation when shaft 40 is rotated. Rounded nose 52 of each block 50 thusalways stays in contact with a ramp 33 of wedge 30.

OPERATION Thus, both first frame 10 and second frame are supported attheir back ends by the large wheels 3. In effect, they are pivotallyjoined together through the axles 3a of wheels 3. The front end ofsecond frame 20 is supported by casters 23. The front end of first frame10 is supported by the front end of second frame 20 through the blocks50 and wedges 30. The blocks 50 and wedges 30 form a cam means betweenfirst frame 10 and second frame 20 whereby the angle between first frame10 and second frame 20 can be increased or decreased. Since theorientation of second frame 20 with respect to the surface being cleanedremains constant, an increase in the aforesaid angle will raise thefront of first frame 10 and accordingly, brush 2 which is located on thefront of first frame 10. Similarly, a decrease in the aforesaid anglewill lower brush 2. More specifically, the rounded nose S2 of each block50 engages ramp 33 of a wedge member 30. When knob 42 is turned, shaft40 is rotated. However, it is fixed against axial movement. When shaft40 rotates, each block 50 is held against rotation by the side walls 62of each channel member 60. Therefore, both blocks to move eithersimultaneously the same distance laterally of the machine, left orright, depending upon the direction the shaft 40 is rotated. As theblocks 50 move, they slide along ramps 33 of their respective wedges 30.Because the noses 52 are rounded, friction between the blocks 50 and thewedges 30 is minimized.

As blocks 50 are moved towards the uppermost ends of ramps 33, secondframe 20 is pivoted about its pivot axis, and the distance between thefront of first frame 10 and the free end of second frame 20 isincreased. Since second frame 20 is supported at one end on the axles 3aof wheels 3, and at the other end on casters 23, the orientation ofsecond frame 20 with respect to the surface being cleaned remainsconstant. Consequently the distance between brush 2, which is located atthe front of frame 10, ahead of frame 20 and at a rather substantialdistance from the pivot axis between first frame 10 and second frame 20,and the surface being cleaned will be increased.

As blocks 50 are moved towards the lowermost ends of wedges 30, thedistance between the front of first frame 10 and second frame 20decreases and consequently brush 2 moves closer to the surface beingcleaned. In order to eliminate the need for blocks 50 having substantialdistance between their tops 55 and their rounded noses 52, notches 34are cut into the uppermost ends of ramps 33 such that shaft 40 cansettle into those notches 34 without engaging the wedges 30 when theblocks 50 are located at the lower ends of the ramps 33.

The mounting of one cam means, Le. a block 50 and wedge 30, on the leftside of the machine, and another cam means located on the right side ofthe machine insures uniform contact between the entire length of brush 2and the surface being cleaned, regardless of the relative height ofbrush 2 with respect to the surface being cleaned. Blocks 50 areadjusted initially on shaft 40 such that the distance between the frames10 and 20 is constant throughout the width of frame 20. In effect then,the weight of first frame 10 is supported at two points, one on eitherside of its center of gravity. These two points are substantially spacedfrom each other. This insures uniform contact between brush 2 and thesurface being cleaned.

As previously pointed out, the orientation of arms 21 with respect tothe surface being cleaned remains constant, regardless of the relativepositions of cams 50 with respect to wedges 30. Also, the pintles ofcasters 23 are mounted vertically in arms 21. This insures that theheight of brush 2 with respect to the surface being cleaned will beconstant regardless of whether the cleaner 1 is being moved forwardly orrearwardly. If the angular relationship of arms 21 changed with changesin the distance between the free ends of frames 10 and 20, then thepintles of casters 23 would not necessarily remain vertically oriented.Consequently, the distance between the free end of second frame 20 andthe surface being cleaned would vary, depending on whether the cleanerwas being moved forwardly or rearwardly. correspondingly, the elevationof the front frame 10, and of brush 2, would vary depending on thedirection of travel.

Thus, it is preferable that the pivoted ends of arms 21 be pivoted onthe axis of rotation of wheels 3. However, this is not absolutelynecessary, provided that arms 21 are sufficiently long that the changein orientation of the pintles of casters 23 varies only slightly withchanges in the respective positions of blocks 50 and wedges 30. If onthe other hand, the arms 21 are short, then the angular orientation ofarms 21 with respect to the surface being cleaned will vary too greatlywith changes in the respective positions of blocks 50 and wedges 30.

Thus, it can be seen that this invention provides a unique means forcontrolling the degree of elevation of a brush from the surface beingcleaned. In addition, it teaches a means whereby the degree of contactbetween that brush and the surface being cleaned remains constantthroughout the length of the brush. Furthermore, the degree of contactbetween the brush and the surface being cleaned remains constantregardless of the direction in which the cleaner is traveling.

Furthermore, these ends are achieved without the need for heavy-dutyframes, complicated lever mechanisms, and other bulky mechanisms.Finally, friction in the system is minimized.

It is understood that the above is merely a preferred embodiment of myinvention and that many changes and alterations can be made thereofwithout departing from the broader aspects and spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

1. A floor-treating machine having a floor-treating element and meansfor regulating the relative elevation of said floortreating elementcomprising: a first frame and a second frame; said first and secondframe pivotally mounted with respect to each other; said floor-treatingelement being mounted on said first frame at a point spaced from thepivot axis between said first and second frames; floor engaging meansfor supporting said machine mounted on said second frame; means forcontrolling the angular spacing between said first frame and said secondframe at a point spaced from said pivot axis comprising at least oneblock mounted to one of said first frame and said second frame and acorresponding wedge mounted on the other of said first and secondframes; means for rectilinearly sliding one of said block and wedge withrespect to the other thereof for varying the angular spacing betweensaid first frame and said second frame and thereby varying the relativeelevation of said floor-treating element with respect to the surfacebeing cleaned.

2. The floor-treating machine described in claim 1 wherein said secondframe extends substantially the full width of said first frame and has afloor contacting support on each side thereof adjacent its free end, apair of said blocks and a pair of said wedges mounted at said free endof said second frame, one of said blocks and one of said wedges beingadjacent each side of said second frame; said sliding means comprisingmeans for simultaneously sliding the slidable one of said pair of blocksand wedges to the same extent on both sides of said machine, therebyvarying the distance between said floortreating element and said surfacebeing cleaned uniformly across the width of said machine.

3. The floor-treating machine described in claim 2 wherein saidfloor-treating element is mounted near one end of said first frame andsaid pivotal mounting between said first frame and said secondary frameis spaced therefrom towards the opposite end of said first frame fromsaid floor-treating element.

4. The floor-treating machine of claim 1 in which a second support meansfor said machine is secured to said first frame near one end thereof,said fioor treating element being mounted near the end of said firstframe opposite from said support for said first frame; said second framebeing pivotally mounted to said first frame at one end of said secondframe; said support means forsaid second frame comprising castersaffixed to the opposite end of said second frame from said pivotalmounting; the distance between said pivoted end of said second frame andsaid castered end of said second frame being sufficiently long that theorientation of said second frame with respect to the surface beingcleaned remains generally constant regardless of the angular spacingbetween said frame means.

5. The floor-treating machine of claim 2 in which a second support meansfor said machine is secured to said first frame near one end thereof,said floor-treating element being mounted near the end of said firstframe opposite from said support for said first frame; said second framebeing pivotally mounted to said first frame at one end of said secondframe; said support means for said second frame comprising castersaffixed to the opposite end of said second frame from said pivotalmounting; the distance between said pivoted end of said second frame andsaid castered end of said second frame being sufiiciently long that theorientation of said second frame with respect to the surface beingcleaned remains generally constant regardless of the angular spacingbetween said frame means.

6. A floor-treating machine having a floor-treating element and meansfor regulating the relative elevation of said floortreating elementcomprising: a first frame and a second frame; said first and secondframe pivotally mounted with respect to each other; said floor-treatingelement being mounted on said first frame at a point spaced from thepivot axis between said first and second frames; floor engaging meansfor supporting said machine mounted on said second frame; means forcamming disposed between said first frame and said second frame at apoint spaced from said pivot axis for controlling the angular spacingbetween said first frame and said second frame; means for actuating saidcam means for varying the angular spacing between said first frame andsaid second frame and thereby varying the relative elevation of saidfloor-treating element with respect to the surface being cleaned andsupport means rotatably mounted on said first frame; said pivotalmounting between said first and second frames being concentric with theaxis of rotation of said rotatable support.

7. A floor-treating machine having a floor-treating element and meansfor regulating the relative elevation of said floortreating elementcomprising: a first frame and a second frame, said second frameextending substantially the full width of said first frame; said firstand second frame pivotally mounted with respect to each other; saidsecond frame including a floorcontacting support on each side thereofadjacent its free end; said floor-treating element being mounted on saidfirst frame at a point spaced from the pivot axis between said firstframe and said second frame; floor engaging means for supporting saidmachine mounted on said second frame; and means for camming disposedbetween said first frame and said second frame at a point spaced fromsaid pivot axis for controlling the angular spacing between said firstframe and said second frame, said camming means comprising a pair ofcams at said free end of said second frame, one of said earns beingadjacent each side of said second frame; means for actuating said cammeans comprising means for simultaneously activating said pair of camsto the same extent on both sides of said machine for varying the angularspacing between said first frame and said second frame and therebyvarying the relative elevation of said floor-treating element withrespect to the surface being cleaned in a uniform manner across thewidth of said machine and support means rotatably mounted on said firstframe; saidpivotal mounting between said first and second frames isconcentric with the axis of rotation of said rotatable support.

8. The floor-treating machine described in claim 7 in which said cammeans includes an inclined ramp and ramp engaging block, one of saidramp and said block being movable with respect to the other for varyingthe position of said block along said ramp.

9. The floor-treating machine described in claim 5 wherein the movableones of said pair of wedges and said pair of blocks are mounted on acommon threaded shaft and are simultaneously shifted an equivalentdistance by rotation of said shaft; said machine including holding meansadjacent each said movable one of said wedge and block such that saidmovable one of said wedge and block is held against rotation when saidthreaded shaft is rotated.

10. The floor-treating machine described in claim 8 wherein the movableone of said ramp and said block of both said cam means are mounted on acommon threaded shaft and are simultaneously shifted an equivalentdistance by rotation of said shaft; said machine including holding meansadjacent the movable one of said ramp and block of both said cam meanssuch that said movable one of said ramp and block is held againstrotation when said threaded shaft is rotated.

11. The floor-treating machine of claim 4 in which said casters havepintles mounted in said second frame perpendicular to said floor; saidpintles maintaining said perpendicular relationship to said supportingsurface throughout the range of actuation of said earns.

12. The floor-treating machine of claim 5 in which said casters havepintles mounted in said second frame perpendicular to said floor; saidpintles maintaining said perpendicular relationship to said supportingsurface throughout the range of actuation of said earns.

13. A cleaner or the like having a floor-treating element and means forregulating the relative elevation of said floor-treating elementcomprising: a first frame; a rotatable support mounted on said firstframe; a second frame having a pair of arms connected by a cross member;each of said arms being pivotally connected to said first frameconcentrically with the axis of rotation of said support; a supportmember mounted on each of said arms at a point spaced from their pivotalmounting; said floor-treating element mounted on said first frame at apoint spaced from said axis of rotation; said second frame having a ramplocated on each of said arms at a point spaced from said axis ofrotation; a threaded shaft mounted on said first frame and extendingover both of said ramps; each of said ramps having a surface inclinedwith respect to said threaded shaft; two block members threaded on saidshaft and held against rotation with respect thereto, each beingadjacent one of said ramps and engaging said inclined surface thereof.

14. The device of claim 13 in which each of said ramps has an open endedslot at the upper end of said inclined surface such that said ramp willnot engage said threaded shaft even with said block at the lower end ofsaid inclined surface.

17. The device of claim 16 in which holding means for said blocks isprovided, said holding means being a channel member fixedly mountedadjacent each of said block members; said channel member having a pairof opposite walls, one on each side of said block member and spacedclosely adjacent thereto.

1. A floor-treating machine having a floor-treating element and meansfor regulating the relative elevation of said floortreating elementcomprising: a first frame and a second frame; said first and secondframe pivotally mounted with respect to each other; said floor-treatingelement being mounted on said first frame at a point spaced from thepivot axis between said first and second frames; floor engaging meansfor supporting said machine mounted on said second frame; means forcontrolling the angular spacing between said first frame and said secondframe at a point spaced from said pivot axis comprising at least oneblock mounted to one of said first frame and said second frame and acorresponding wedge mounted on the other of said first and secondframes; means for rectilinearly sliding one of said block and wedge withrespect to the other thereof for varying the angular spacing betweensaid first frame and said second frame and thereby varying the relativeelevation of said floor-treating element with respect to the surfacebeing cleaned.
 2. The floor-treating machine described in claim 1wherein said second frame extends substantially the full width of saidfirst frame and has a floor contacting support on each side thereofadjacent its free end, a pair of said blocks and a pair of said wedgesmounted at said free end of said second frame, one of said blocks andone of said wedges being adjacent each side of said second frame; saidsliding means comprising means for simultaneously sliding the slidableone of said pair of blocks and wedges to the same extent on both sidesof said machine, thereby varying the distance between saidfloor-treating element and said surface being cleaned uniformly acrossthe width of said machine.
 3. The floor-treating machine described inclaim 2 wherein said floor-treating element is mounted near one end ofsaid first frame and said pivotal mounting between said first frame andsaid secondary frame is spaced therefrom towards the opposite end ofsaid first frame from said floor-treating element.
 4. The floor-treatingmachine of claim 1 in which a second support means for said machine issecured to said first frame near one end thereof, said floor-treatingelement being mounted near the end of said first frame opposite fromsaid support for said first frame; said second frame being pivotallymounted to said first frame at one end of said second frame; saidsupport means for said second frame comprising casters affixed to theopposite end of said second frame from said pivotal mounting; thedistance between said pivoted end of said second frame and said casteredend of said second frame being sufficiently long that the orientation ofsaid second frame with respect to the surface being cleaned remainsgenerally constant regardless of the angular spacing between said framemeans.
 5. The floor-treating machine of claim 2 in which a secondsupport means for said machine is secured to said first frame near oneend thereof, said floor-treating element being mounted near the end ofsaid first frame opposite from said support for said first frame; saidsecond frame being pivotally mounteD to said first frame at one end ofsaid second frame; said support means for said second frame comprisingcasters affixed to the opposite end of said second frame from saidpivotal mounting; the distance between said pivoted end of said secondframe and said castered end of said second frame being sufficiently longthat the orientation of said second frame with respect to the surfacebeing cleaned remains generally constant regardless of the angularspacing between said frame means.
 6. A floor-treating machine having afloor-treating element and means for regulating the relative elevationof said floor-treating element comprising: a first frame and a secondframe; said first and second frame pivotally mounted with respect toeach other; said floor-treating element being mounted on said firstframe at a point spaced from the pivot axis between said first andsecond frames; floor engaging means for supporting said machine mountedon said second frame; means for camming disposed between said firstframe and said second frame at a point spaced from said pivot axis forcontrolling the angular spacing between said first frame and said secondframe; means for actuating said cam means for varying the angularspacing between said first frame and said second frame and therebyvarying the relative elevation of said floor-treating element withrespect to the surface being cleaned and support means rotatably mountedon said first frame; said pivotal mounting between said first and secondframes being concentric with the axis of rotation of said rotatablesupport.
 7. A floor-treating machine having a floor-treating element andmeans for regulating the relative elevation of said floor-treatingelement comprising: a first frame and a second frame, said second frameextending substantially the full width of said first frame; said firstand second frame pivotally mounted with respect to each other; saidsecond frame including a floor contacting support on each side thereofadjacent its free end; said floor-treating element being mounted on saidfirst frame at a point spaced from the pivot axis between said firstframe and said second frame; floor engaging means for supporting saidmachine mounted on said second frame; and means for camming disposedbetween said first frame and said second frame at a point spaced fromsaid pivot axis for controlling the angular spacing between said firstframe and said second frame, said camming means comprising a pair ofcams at said free end of said second frame, one of said cams beingadjacent each side of said second frame; means for actuating said cammeans comprising means for simultaneously activating said pair of camsto the same extent on both sides of said machine for varying the angularspacing between said first frame and said second frame and therebyvarying the relative elevation of said floor-treating element withrespect to the surface being cleaned in a uniform manner across thewidth of said machine and support means rotatably mounted on said firstframe; said pivotal mounting between said first and second frames isconcentric with the axis of rotation of said rotatable support.
 8. Thefloor-treating machine described in claim 7 in which said cam meansincludes an inclined ramp and ramp engaging block, one of said ramp andsaid block being movable with respect to the other for varying theposition of said block along said ramp.
 9. The floor-treating machinedescribed in claim 5 wherein the movable ones of said pair of wedges andsaid pair of blocks are mounted on a common threaded shaft and aresimultaneously shifted an equivalent distance by rotation of said shaft;said machine including holding means adjacent each said movable one ofsaid wedge and block such that said movable one of said wedge and blockis held against rotation when said threaded shaft is rotated.
 10. Thefloor-treating machine described in claim 8 wherein the movable one ofsaid ramp and said block of both said cam means are mounted on a commonthreaded shaft and are simultaneously shifted an equivalent distance byrotation of said shaft; said machine including holding means adjacentthe movable one of said ramp and block of both said cam means such thatsaid movable one of said ramp and block is held against rotation whensaid threaded shaft is rotated.
 11. The floor-treating machine of claim4 in which said casters have pintles mounted in said second frameperpendicular to said floor; said pintles maintaining said perpendicularrelationship to said supporting surface throughout the range ofactuation of said cams.
 12. The floor-treating machine of claim 5 inwhich said casters have pintles mounted in said second frameperpendicular to said floor; said pintles maintaining said perpendicularrelationship to said supporting surface throughout the range ofactuation of said cams.
 13. A cleaner or the like having afloor-treating element and means for regulating the relative elevationof said floor-treating element comprising: a first frame; a rotatablesupport mounted on said first frame; a second frame having a pair ofarms connected by a cross member; each of said arms being pivotallyconnected to said first frame concentrically with the axis of rotationof said support; a support member mounted on each of said arms at apoint spaced from their pivotal mounting; said floor-treating elementmounted on said first frame at a point spaced from said axis ofrotation; said second frame having a ramp located on each of said armsat a point spaced from said axis of rotation; a threaded shaft mountedon said first frame and extending over both of said ramps; each of saidramps having a surface inclined with respect to said threaded shaft; twoblock members threaded on said shaft and held against rotation withrespect thereto, each being adjacent one of said ramps and engaging saidinclined surface thereof.
 14. The device of claim 13 in which each ofsaid ramps has an open ended slot at the upper end of said inclinedsurface such that said ramp will not engage said threaded shaft evenwith said block at the lower end of said inclined surface.
 15. Thedevice of claim 13 in which stop means is located on said threadedshaft, at least one such stop means being located on either side of oneof said block members to restrict the length of travel of said blockmember.
 16. The device of claim 14 in which stop means is located onsaid threaded shaft, at least one such stop means being located oneither side of one of said block members to restrict the length oftravel of said block member.
 17. The device of claim 16 in which holdingmeans for said blocks is provided, said holding means being a channelmember fixedly mounted adjacent each of said block members; said channelmember having a pair of opposite walls, one on each side of said blockmember and spaced closely adjacent thereto.